The ProSafe 750 uses a key-card locking mechanism to unlock. To unlock, insert either of the punched corners of the card into the lock slot from the top of the slot without any clearance at 90 degree position. Press firmly until lock snaps open. To lock it, simply press shackle to close. Keep a note of the key-card code stamped underneath the key-card. Contact our customer service and quote this key-code for replacement. The advantages are that you don"t have to keep extra keys with you and you don"t have to remember any code. Travel Sentry Approved locks can be opened and relocked by Transport Security Administration (TSA) agents in all US commercial airports during baggage inspection. Anti-theft Features Travel Sentry® Approved Zinc alloy Unlocks using coded key-card Key-card can be kept conveniently in wallet 2 x credit card sized key-cards included